XML (Extensible Markup Language) is a flexible, text-based format used to store and transport data. Designed to be both human-readable and machine-readable, XML allows users to define their own tags and data structures, making it highly adaptable for various applications. It is commonly used for data exchange between systems, configuration files, and web services. XML documents are structured in a hierarchical tree, with elements enclosed in angle brackets, enabling clear organization and easy parsing of complex information.